Brain Rules (Updated and Expanded)

Catwoman
, and we in our nifty little submarine are viewing their
brains while they watch. Even though the twins are in the same room,
sitting on the same couch, the twins see the movie from slightly different
angles. We find that their brains are encoding visual memories of the video
differently, in part because it is impossible to observe the video from the
same spot. Seconds into the movie, they are already wiring themselves
differently. One of the twins earlier in the day read a magazine story about
panned action movies, a picture of Berry figuring prominently on the cover.
While watching the video, this twin’s brain is simultaneously accessing
memories of the magazine story. We observe that his brain is busy
comparing and contrasting comments from the text with the movie and is
assessing whether he agrees with them. The other twin has not seen this
magazine, so his brain isn’t doing this. Even though the difference may
seem subtle, the two brains are creating different memories of the same
movie.
That’s the power of the Brain Rule. Learning results in physical changes
in the brain, and these changes are unique to each individual. Not even
identical twins having identical experiences possess brains that wire
themselves exactly the same way. Given this, can we know 
anything
about
the organ? Well, yes. The brain has billions of cells whose collective
electrical efforts work in a similar fashion. Every human comes equipped
with a hippocampus, a pituitary gland, and the most sophisticated thinking
store of electrochemistry on the planet: a cortex. These tissues function the
same way in every brain. How then can we explain the individuality?
Consider a highway.
For each brain, a different road map
The United States has one of the most extensive and complex ground
transportation systems in the world. There are lots of variations on the idea
of “road,” from interstate freeways, turnpikes, and state highways to

---

residential streets, one-lane alleys, and dirt roads. Pathways in the human
brain are similarly diverse. We have the neural equivalents of large
interstate freeways, turnpikes, and state highways. These big trunks are the
same from one person to the next, functioning in yours about the same way
they function in mine. So a great deal of the structure and function of the
brain is predictable. This may be the ultimate result of the double-humped
growth and pruning program we talked of previously. That’s the experience-
independent wiring.
It’s when you get to the smaller routes—the brain’s equivalent of
residential streets, one-laners and dirt roads—that individual patterns begin
to show up. In no two people are they identical. That’s the experience-
dependent wiring. Every brain has a lot of these smaller paths, which is why
the very small amounts to a big deal. It’s why, for example, human intellect
is so multifaceted. Psychologist Howard Gardner believes we have at least
seven categories of intelligence: verbal/linguistic, musical/rhythmic,
logical/mathematical, spatial, bodily/kinesthetic, interpersonal, and
intrapersonal. It’s a much broader idea of intelligence than the standard IQ
test implies.
We can grasp the magnitude of each brain’s differences by watching a
skilled neurosurgeon at work. George Ojemann has a shock of white hair,
piercing eyes, and the quiet authority of someone who for decades has
watched people live and die in the operating room. He is one of the great
neurosurgeons of our time, and he is an expert at a technique called
electrical stimulation mapping.
Ojemann is hovering over the exposed brain of a man with severe
epilepsy. The man’s name is Neil. Ojemann is there to remove some of
Neil’s misbehaving brain cells. Before Ojemann takes anything out,
however, he has to make a map. To do this, he needs to talk to Neil during
surgery, so Neil is fully conscious. Fortunately, the brain has no pain
receptors. Ojemann wields a thin silver wire, which sends out small,
unobtrusive electrical shocks to anything it touches. If it brushed against
your hand, you would feel only a slight tingling sensation. Ojemann gently
touches one end of the wire to an area of his patient’s brain. In the book